The drive itself can determine provide it's own IC. The internal IC is set during it's auto-tune procedure. While internal IC is automatic, it may be the most difficult to set correctly. This method requires the least engineering, but the most careful commissioning. We cannot trust auto-tuning to provide the best IC possible.

IC internal to the drive does not use the acceleration from the Controller’s S Ramp. Instead the drive determines the acceleration by calculating the derivative of the speed reference or feedback. The derivative may produce a noisy signal which will show as torque pulses during speed changes.​A number of factors affect the accuracy of setting IC by this method. The most important is the lag introduced by the speed filter in the drive. I suggest temporarily eliminating the speed feedback filter for this procedure, although this may introduce additional noise in the derivative calculation, depending on how the derivative is performed.

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Clarence Klassen

This Technical Topic Channel presents information of interest to electrical engineers, electrical maintenance and project managers involved with web handling. It is moderated by Clarence Klassen, and includes White Papers, questions from readers and comments on industry issues.